1. Field of the Invention
This invention concerns writing instruments and in particular reservoir pens.
2. Description of the Prior Art
The majority of pens available on the market are designed to lay down an ink trace of substantially constant width. However, it is often required to draw lines of different controlled widths. In order to meet this need, there has been proposed a pen with a body to which may be attached any one of a series of writing heads fitted with nibs of different sizes. The need to replace the writing head each time the line width is to be changed is very inconvenient. It is also known to provide a pen with a broad nib so that lines of variable width can be produced by moving the pen across the paper with the nib at different angles to the direction of movement. In this case considerable skill and dexterity are required to produce lines of uniform width.
According to another prior proposal, an inner nib is located within a tubular outer nib and is biased forwardly by a spring. Under light writing pressure, the inner nib is operative, but by increasing the pressure, it can be retracted so that the tubular outer nib takes over. With a pen of this construction, much skill is also required to write continuously with an ink trace of the desired width.